The Great Engine Builder Debate in Lo206

So…was anyone caught twisting with the new cam rules at the Spring Nationals??

New to karting and 206 specifically. What is the price range on a new “built” engine from the popular 206 builders?

Right now, it appears to be about $1200-$1400 for a complete package (engine, exhaust, air filter, fuel lines, chain guard). Add your motor mount and clutch.

I really hate to beat a dead horse, but I’m a data nerd when it comes to this type of stuff. Does anyone have dyno numbers to compare a “built” engine vs out-of-the-box?

I bought my first kart back in April, and have been racing it pretty hard this year. I’ve done just about every OVKA race as well as a couple long practices at G&J Kartway. Its a 2019 Birel Am29 and it came with a 206 prepped by Kart City Performance. The guys I bought it from were pretty hardcore racers too so its definitely due for a refresh once the seasons over. I haven’t done a single thing to it other than oil changes and clutch cleanings after each race-day. I’ve cleaned the carb like, once. Rather than draining and cleaning between races I just start the engine for a few minutes every few days so the fuel doesn’t get stagnant in the bowl. I’ve had zero issues and the engine itself feels fine.

I’m curious on what the differences are between a prepped motor vs a stock one considering the briggs rule-set is very strict. Now, I’m not dis-crediting those who do build engines here. There’s definitely a peace of mind knowing you’re getting something that’s verified and ready to race, and getting extra technical support. But for the DIY’ers like myself who enjoy tinkering in the garage … is it really necessary? The money I’d spend sending the engine off somewhere, or the cost difference between buying a prepped engine vs a stock one, can easily be put towards another set of tires or entry fees for the next few races, which I find more value in since I’m relatively new.

It really depends. Generally I would say it’s not totally necessary at first. But as you start to look for small amounts of time here and there it might be time to look it it.

I spent an afternoon pouring over dyno data a couple of weekends ago with a builder. We did a back to back runs with a brand new 206 out of the box followed by my 30hr (abused) 2019 one. There was about .4 HP difference… however that was resolved with correcting the valve lash and getting the carb dialed in.

I look at having an engine prepped as a final QC check and a service plan of sorts.

I would say that trying to find the same performance variances and then correcting them might be difficult without a dyno. Sure, the track is a dyno too… but with such small differences it’s hard to tell the pertinent data apart from the variables.

In short: For your first few races run it outta the box, hire a coach and go from there.

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Like @Jayrdee I’d love to see data from engine builders that shows engine curve as received and then after tuning.

I’ll see if I can find mine from when we took a 206 with unknown history. Graph shows between 0.3 and 0.4 HP across the entire range.

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I use a local reputable engine builder to take one less variable out of my racing! Box stock motors win too. The peace of mind of knowing my engine is assembled and gone over by someone who knows way more than I do is what I pay for.


I hear you… But, but, but, the bottom end is sealed. Presumably, all engines are run at Briggs before shipping out.

So, whatever is going on must be happening during shipping?

They don’t run at Briggs.


Sometimes the float or inlet needle may stick. But at the end of the day, the engines leave Briggs at Milwaukee built to certain mechanical tolerances.

These are good enough for most racers most of the time. But there are improvements that can be made without breaking any rules. Ensuring the fuel curve is optimal is one example by trying different needle heights and air screw settings. Each engine and carb seems to have its own sweet spot. But again, I stress the improvements are fairly small in the grand scheme of things. It’s unlikely to make a mid pack driver a podium one.

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I have 3 engines from 3 different builders. A black seal 2015 GT Machine, 2021 AEM and a 2022 VP Racing. None of these have improved my lap times in a measurable way. Pounding out laps improving my lines, braking points and quieting down my hands coupled with chassis tuning and proper tire pressures and rear track depending on the track grip and temperature that day is what has shaved seconds off my times from when I started. It’s like has been said to me before…as a newer driver the first few seconds came relatively quickly over a few months hitting the track as much as possible. Lately I’m chasing 10ths to get to the fastest guys in my heavy class. I’ve tried all 3 engines at one point or another on the weighted kart I race regularly and they’re all consistent. In the end, it’s always my driving that nets less than ideal pace. But, as a default I just blame the kart every time :rofl:


Thank you for sharing - very helpful.

This is my first season, and I was very fortunate that during a practice session three other drivers in it club drove my kart to give me suggestions. It was great because the lap times they were because of the driver. I have my work cut out for me!

This is what I like to hear. I’m like you, I know my driving along with the kart setup is what yields the most improvements.

It seems like the general consensus is there’s not much of a difference between box-stock and prepped 206 engines, which is great news for the late-night mechanics like myself who enjoy working on stuff in the garage.


A .4 HP increase on the advertised 9HP is 4.4% increase. Just sayin’.

When your driving skill is the same as the guy you’re racing… :grin:

I am of the opinion there are good engines and bad ones. All motors will run decently, but definitely some that just make power.

The best engine I ran was .6 tenths faster and could pull 2 teeth less (219) then my current engine. That is a significant difference.

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There are normal engines and very few outliers on either side of average.

Alan, you are absolutely correct. Not all parts come from the factory the same. Anomalies occur and some specs are better than others and just perform better. If you are a builder, you know there are differences, and you learn what to look for as far as fast numbers. What happens from there is a matter of integrity.

Briggs is supposed to have data on all new motors. Builders know what to expect from “normal” box stock tolerances.

I’m just baffled by all of this. I just don’t understand the reward, I guess. Winning by cheating has never been winning and it feels empty. Just why? (Racing for $ not included in this discussion).

For a long time I was the pre-eminent Hibernian assassin on my server in DAOC. I was aware others around me were using X-Unleashed (radar app) to gain a huge edge in combat (initiative). I played clean.

Towards the end of the games life-cycle, I joined in the fun, using the radar app. It kind of sucked all the fun out of the game, removing the element that made playing a stealthy assassin interesting,… the art of tracking and hunting down the vulnerable enemies.

Cheating made the game… basic. Cheating gave more instant pleasure at the cost of achievement, if that makes sense.

I suspect it does the same to karting.

I am wondering if varying valve lash would be beneficial when you are running on a different track configurations (ie tight technical track to a more fast flowing track)